Polytetrafluoroethylene (PTFE) co-polymers are well known in the art. PTFE co-polymers are of great use in many industries, but are particularly useful in medical applications due to their inertness and biocompatibility.
While useful in many respects, utilizing PTFE copolymers in solution for medical applications poses difficulties. PTFE copolymers that are water soluble are not useful for medical applications because they are not as inert or resistant to dissolution in an aqueous environment. On the other hand, PTFE copolymers that are insoluble in water are very hydrophobic, which is also problematic. In particular, the solvents used to solubilize these types of tetrafluoroethylene co-polymers can be highly toxic or otherwise detrimental to living tissue. Thus, using such a solution in vivo may not be an ideal scenario.
In addition, because of the hydrophobic nature of insoluble PTFE copolymers, mixing these copolymers with a hydrophilic therapeutic agent is also difficult because the solvents suitable to dissolve PTFE copolymers are generally not suitable to dissolve hydrophilic agents. One approach for mixing a hydrophilic agent with PTFE-copolymer is to form a colloid, such as an emulsion. To be useful for a medical application, however, the drug emulsion should be relatively kinetically-stable. The very hydrophobic nature of the fluoropolymers makes forming a stable emulsion difficult without the use of a surfactant or a cosolvent to control the chemical and thermodynamic instabilities. In fact, the use of combining surfactants and fluoropolymer is the conventional way to form a PTFE emulsion. Little is known however about how to do so without a surfactant or a cosolvent, especially with cosolvents or surfactants that have a low toxic potential.
Thus, there is a need to be able to formulate polytetrafluoroethylene copolymers in less harmful solvents and/or to be able to admix hydrophilic agents with these polytetrafluoroethylene co-polymers. In particular, there is a need to be able to formulate polytetrafluoroethylene co-polymers in low toxicity solvents, such as those solvents classified by the FDA as “Solvents with Low Toxic Potential (Class III Solvents).”
Preferably, it would be desirable to be able to form kinetically stable emulsions with fluoropolymers without the addition of another component, such as a surfactant, but with the polymer material itself serving as a biocompatible surfactant for formulations comprising hydrophilic agents.